American-born spy and code-breaker extraordinaire Maggie Hope must solve a baffling series of murders among a group of captive agents on an isolated Scottish island, as the acclaimed World War II mystery series from New York Times bestselling author Susan Elia MacNeal continues.

World War II is raging, and former spy Maggie Hope knows too much.

She knows what the British government is willing to do to keep its secrets.

She knows the real location of the planned invasion of France.

She knows who's lying. She knows who the double-crossers are. She knows exactly who is sending agents to their deaths.

These are the reasons Maggie is isolated on a remote Scottish island, in a prison known as Killoch Castle, out of contact with friends and family.

Then one of her fellow inmates drops dead in the middle of his after-dinner drink--and he's only the first. As victims fall one by one, Maggie will have to call upon all her wits and skills to escape--not just certain death...but certain murder.

For what's the most important thing Maggie Hope knows?

She must survive.

This description comes from the publisher. The Prisoner in the Castle is the eighth book in the Maggie Hope series, the first of which is Mr. Churchill's Secretary.